講演情報
[7p-P03-22]Spatial mapping of effective magnetic field at the Py/NiO interface
〇(D)Itaru Sugiura1, Yoichi Shiota1,2, Ryusuke Hisatomi1,2, Shutaro Karube1,2, Teruo Ono1,2, Takahiro Moriyama3,4 (1.ICR, Kyoto Univ., 2.CSRN, Kyoto Univ., 3.PRESTO, JST, 4.Nagoya Univ.)
キーワード：
antiferromagnet、magnetic domain、ferromagnetic resonance
Antiferromagnets have attracted attention in spintronics owing to their robustness against external perturbations, absence of stray field, and capability for ultra-fast operation. Although understanding of domain states is essential for advancing performance of antiferromagnet-based devices, observation techniques for these domains are currently limited owing to the negligible spontaneous magnetization. It is still desirable to develop accessible techniques for imaging antiferromagnetic domains. In this study, we developed a spatial imaging technique for antiferromagnetic domains by heterodyne-magneto-optical-Kerr (MOKE) measurements taking advantage of magnetization dynamics of a ferromagnets adjacent to antiferromagnet.
Thin multilayer NiO (30 nm)/Ni80Fe20 (5 nm)/Cu (3 nm)/SiO2 (3 nm) was deposited on a single crystalline MgO(001) substrate by magnetron sputtering. The film was patterned into a 4-µm-wide strip attached to a coplanar waveguide. Fig. 1(a) shows the magnetization dynamics measurement set-up with simultaneous electrical homodyne detection and optical heterodyne detection. Fig. 1(b) spatially maps the amplitude |S21| of the optical signal from the polar Kerr effect which depicts the area where the ferromagnetic resonance of NiFe is excited with the in-plane magnetic field μ0Hext = 50 mT with the angle φ = 45° and 135° and the microwave frequency f = 10 GHz. The contrast observed for φ = 45° and 135° suggests that an anisotropy field acting on NiFe is spatially distributed by the underlying T-domains of NiO. The field directions φ = 45° and 135° respectively correspond to the in-plane projection of preferential Néel vector orientations in NiO[-110] and [-1-10] of the epitaxial NiO. In the presentation, we will discuss the T-domain distribution of the NiO and validity of our measurement technique.
Thin multilayer NiO (30 nm)/Ni80Fe20 (5 nm)/Cu (3 nm)/SiO2 (3 nm) was deposited on a single crystalline MgO(001) substrate by magnetron sputtering. The film was patterned into a 4-µm-wide strip attached to a coplanar waveguide. Fig. 1(a) shows the magnetization dynamics measurement set-up with simultaneous electrical homodyne detection and optical heterodyne detection. Fig. 1(b) spatially maps the amplitude |S21| of the optical signal from the polar Kerr effect which depicts the area where the ferromagnetic resonance of NiFe is excited with the in-plane magnetic field μ0Hext = 50 mT with the angle φ = 45° and 135° and the microwave frequency f = 10 GHz. The contrast observed for φ = 45° and 135° suggests that an anisotropy field acting on NiFe is spatially distributed by the underlying T-domains of NiO. The field directions φ = 45° and 135° respectively correspond to the in-plane projection of preferential Néel vector orientations in NiO[-110] and [-1-10] of the epitaxial NiO. In the presentation, we will discuss the T-domain distribution of the NiO and validity of our measurement technique.